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Subject[PATCH 2/3] arm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling
Date
From: "Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org>

Add VM_FAULT_HWPOISON[_LARGE] handling to the arm64 page fault
handler. Handling of VM_FAULT_HWPOISON[_LARGE] is very similar
to VM_FAULT_OOM, the only difference is that a different si_code
(BUS_MCEERR_AR) is passed to user space and si_addr_lsb field is
initialized.

Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
(fix new __do_user_fault call-site)
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
---
arch/arm64/mm/fault.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 1b35b8bddbfb..7684219d8cc4 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -31,6 +31,7 @@
#include <linux/highmem.h>
#include <linux/perf_event.h>
#include <linux/preempt.h>
+#include <linux/hugetlb.h>

#include <asm/bug.h>
#include <asm/cpufeature.h>
@@ -207,10 +208,11 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
*/
static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
unsigned int esr, unsigned int sig, int code,
- struct pt_regs *regs)
+ struct pt_regs *regs, int fault)
{
struct siginfo si;
const struct fault_info *inf;
+ unsigned int lsb = 0;

if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
inf = esr_to_fault_info(esr);
@@ -227,6 +229,17 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
si.si_errno = 0;
si.si_code = code;
si.si_addr = (void __user *)addr;
+ /*
+ * Either small page or large page may be poisoned.
+ * In other words, VM_FAULT_HWPOISON_LARGE and
+ * VM_FAULT_HWPOISON are mutually exclusive.
+ */
+ if (fault & VM_FAULT_HWPOISON_LARGE)
+ lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
+ else if (fault & VM_FAULT_HWPOISON)
+ lsb = PAGE_SHIFT;
+ si.si_addr_lsb = lsb;
+
force_sig_info(sig, &si, tsk);
}

@@ -242,7 +255,7 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
*/
if (user_mode(regs)) {
inf = esr_to_fault_info(esr);
- __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs);
+ __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs, 0);
} else
__do_kernel_fault(mm, addr, esr, regs);
}
@@ -444,6 +457,9 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
*/
sig = SIGBUS;
code = BUS_ADRERR;
+ } else if (fault & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) {
+ sig = SIGBUS;
+ code = BUS_MCEERR_AR;
} else {
/*
* Something tried to access memory that isn't in our memory
@@ -454,7 +470,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
SEGV_ACCERR : SEGV_MAPERR;
}

- __do_user_fault(tsk, addr, esr, sig, code, regs);
+ __do_user_fault(tsk, addr, esr, sig, code, regs, fault);
return 0;

no_context:
--
2.11.0
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